[en] In relativistic heavy ion collisions, the features of two distinct and symmetric peaks with respect to rapidity y of net baryon distributions are shown in the CERN Super Proton Synchrotron (SPS), BNL Relativistic Heavy Ion Collider (RHIC) "["1"-"6"] and CERN Large Hadron Collider (LHC) energy regions. The rapidity separation between the peaks increases with energy and decreasing with increasing mass number, A, reflecting larger baryon stopping for heavier nuclei, as was investigated phenomenologically in the Non-Uniform Flow Model (NUFM) "["7"-"1"0"]. In this work we show how the evolution of the peaks can be linked to saturation physics. The net-baryon number is essentially transported by valence quarks that probe the saturation regime in the target by multiple scattering. During the collisions, the fast valence quarks in one nucleus scatter in the other nucleus by exchanging soft gluons, leading to their redistribution in rapidity space. The valence quark distribution is well known at large x, which relates to the forward and backward rapidity regions. The gluon distribution is given by small x in the target nucleus. Comparing with Ref "["1"1"], we also investigate net baryon distributions in the SPS and RHIC energy regions by taking advantage of the effective quark mass. Predications for net-baryon rapidity distributions and the mean rapidity loss in central Pb + Pb collisions at LHC are made in this paper. (authors)